Cytokines, chemokine receptors, and homing molecule distribution in the rectum and stomach of pediatric patients with ulcerative colitis.

BACKGROUND: Cytokines appear to play a significant role in the pathogenesis of inflammatory bowel disease (IBD) with a predominant Th2 pattern in colonic mucosa of patients with ulcerative colitis (UC). Chemokines and their receptors also regulate the migration of Th1 or Th2 lymphocytes to inflammatory tissues during the immune response. Although adult UC is usually confined to the colon, pediatric UC not uncommonly affects the stomach. AIMS: The aim of this study was to compare expression of cytokines, chemokine receptors, and homing molecules in the rectal and the histologically characterized gastric mucosa of pediatric patients with UC. SUBJECTS Sixteen patients (11 girls and 5 boys; median age, 9 years) having all the features of UC were included in the study. METHODS: Rectal and gastric mucosa obtained from UC cases were immunostained with antibodies against L-selectin, beta 7 integrin, CXCR3, CCR3, and CCR5. IL-4 and IL-12 p40 transcript expression was studied by in situ hybridization. RESULTS: Chronic gastritis was found in 93.7% of cases and Helicobacter pylori (Hp) was found in 2 (13.3%) cases. In the rectal and gastric mucosa, CXCR3 was found in perivascular lymphocytes and CCR5 in a subset of CXCR3+ cells in the lamina propria. CCR3+ lymphocytes and IL-4-positive cells were always found, but there was no evidence of IL-12 production. Most of the lymphocytes infiltrating the gastric mucosa expressed beta 7 but not CD62L. In contrast, beta 7-positive cells were randomly dispersed in the rectal lamina propria, and the fraction of CD3+beta 7+ was low. CONCLUSIONS: The authors conclude that gastritis is common in pediatric UC. The presence of CCR3+ lymphocytes, IL-4 transcript expression, without IL-12 p40 production in the stomach and in the rectum suggests a Th2 immune response. The presence of CCR3+, CD62L- activated Th2 cells may suggest that these gastric cells are recruited from colorectal primary lesions.

Preferential and persistent depletion of CCR5+ T-helper lymphocytes with nonlymphoid homing potential despite early treatment of primary HIV infection.

Strains of human immunodeficiency virus (HIV) transmitted between individuals use the CCR5 coreceptor, but no preferential depletion of particular Th-lymphocyte subpopulations has been reported during primary HIV infection (PHI). In contrast, gut-associated Th lymphocytes are preferentially depleted in macaques recently infected by simian immunodeficiency virus. The expression of CCR5 and the intestinal homing receptor integrin alpha4beta7 on subpopulations of Th lymphocytes was studied in 12 patients with PHI. There was a profound decrease of circulating alpha4beta7+ Th lymphocytes and CCR5+ memory Th lymphocytes with nonlymphoid homing potential (CD62L-CD45RO+). Unlike other Th lymphocytes, this cell population remained depleted despite early control of viral replication under antiretroviral treatment. Therefore, HIV preferentially targets a specific CCR5+ subpopulation of Th lymphocytes early during infection, inducing its persistent depletion despite treatment. Protective immunity in vivo depends on Th lymphocytes carrying homing capacity to nonlymphoid tissue, and therefore these data may explain the persistent abnormalities of immune functions in patients infected with HIV.

Deregulation of the expression of the fractalkine/fractalkine receptor complex in HIV-1-infected patients.

Fractalkine is the only member of the CX3C chemokine family. Polymorphism of the fractalkine receptor gene may influence the prognosis of human immunodeficiency virus (HIV) infection, but the nature of the cells expressing fractalkine or its receptor in HIV-infected patients remains unknown. We show that, in contrast to HIV-uninfected individuals, a large number of cells expressed fractalkine in T-cell zones of lymph nodes from HIV-infected patients. CD83(+) mature and CD123(+) plasmacytoid dendritic cells as well as plasma cells are involved in this increased expression of fractalkine. Increased numbers of plasmacytoid dendritic cells and plasma cells were present in T-cell zones of HIV-infected patients. CD83(+) dendritic cells were present in similar number in HIV-infected patients and controls, but an increased fraction of these cells produced fractalkine in HIV-infected patients. Many plasma cells in the gut-associated lymphoid tissue from HIV-infected patients also produced fractalkine, whereas few cells produced fractalkine in the gut of controls. The fraction of CD45RO(+) and CD45RO(-) T helper (Th) cells expressing the fractalkine receptor CX3CR1 was higher in HIV-infected patients than in healthy individuals, and these cells were abnormally sensitive to fractalkine stimulation. This increased response correlated with HIV viremia, and it returned to normal levels in patients successfully treated with antiretroviral drugs. The increased expression of the fractalkine/fractalkine receptor complex associated with HIV infection may affect adhesion and migration of Th lymphocytes and their interaction with dendritic cells. Thus, it may influence the equilibrium between depletion and renewal of the Th lymphocyte compartment.

Production of stromal cell-derived factor 1 by mesothelial cells and effects of this chemokine on peritoneal B lymphocytes.

B1a lymphocytes accumulate and proliferate in the peritoneal cavity. Stromal cell-derived factor 1 (SDF-1) is a chemotactic and growth promoting factor for B cell precursors. It is required for fetal liver B cell lymphopoiesis, which generates mostly B1a lymphocytes. Using immunohistochemistry with an anti-SDF-1 monoclonal antibody, we found that SDF-1 was produced by peritoneal mesothelial cells in adult mice. Peritoneal B1a lymphocytes expressed a functional SDF-1 receptor, as shown by actin polymerization experiments. In vitro, SDF-1 stimulated migration, proliferation of a minority of peritoneal B1a lymphocytes, and prevented apoptosis in a large fraction of cells. B1a cells migrating in response to SDF-1 were largely enriched in the CD5(high)CD43(high)B220(-)CD1d(-) subpopulation. In vivo, neutralization of SDF-1 for 3 weeks significantly decreased the number of peritoneal B1 cells. SDF-1 also acted on peritoneal B2 cells. These findings show that after the cessation of B cell lymphopoiesis in the liver, around birth, the persistence of B1a cells remains SDF-1 dependent, and that SDF-1 production by mesothelial cells plays a role in the peritoneal location of B1a cells. Thus, the role of mesothelial cells for B1a cells in adults may be similar to that of SDF-1-producing biliary ductal plate cells in the fetus, and to that of bone marrow stromal cells for B2 cell precursors.

Regulation of CCR6 chemokine receptor expression and responsiveness to macrophage inflammatory protein-3alpha/CCL20 in human B cells.

The regulation of CCR6 (chemokine receptor 6) expression during B-cell ontogeny and antigen-driven B-cell differentiation was analyzed. None of the CD34(+)Lin(-) hematopoietic stem cell progenitors or the CD34(+)CD19(+) (pro-B) or the CD19(+)CD10(+) (pre-B/immature B cells) B-cell progenitors expressed CCR6. CCR6 is acquired when CD10 is lost and B-cell progeny matures, entering into the surface immunoglobulin D(+) (sIgD(+)) mature B-cell pool. CCR6 is expressed by all bone marrow-, umbilical cord blood-, and peripheral blood-derived naive and/or memory B cells but is absent from germinal center (GC) B cells of secondary lymphoid organs. CCR6 is down-regulated after B-cell antigen receptor triggering and remains absent during differentiation into immunoglobulin-secreting plasma cells, whereas it is reacquired at the stage of post-GC memory B cells. Thus, within the B-cell compartment, CCR6 expression is restricted to functionally mature cells capable of responding to antigen challenge. In transmigration chemotactic assays, macrophage inflammatory protein (MIP)-3alpha/CC chemokine ligand 20 (CCL20) induced vigorous migration of B cells with differential chemotactic preference toward sIgD(-) memory B cells. These data suggest that restricted patterns of CCR6 expression and MIP-3alpha/CCL20 responsiveness are integral parts of the process of B-lineage maturation and antigen-driven B-cell differentiation.

Pretreatment expression of the perforin gene by circulating CD8(+) T lymphocytes predicts biochemical response to interferon-alpha in patients with chronic hepatitis C.

It would be of great value to be able to predict, before the initiation of treatment, which patients with hepatitis C virus-induced chronic hepatitis will be cured by interferon-alpha (IFN-alpha). Competitive RT-PCR was used to evaluate spontaneous expression of the perforin gene, a marker of cytotoxic cell activation, by circulating mononuclear cells in 17 patients undergoing IFN-alpha treatment. IFN-alpha increased perforin gene expression (p < 0.003), but this was not correlated with outcome. In contrast, pretreatment perforin gene expression levels were higher in the 8 patients with a sustained biochemical response after treatment than in the 9 non-responsive patients (p = 0.01). This factor predicted favorable clinical outcome with a sensitivity of 75% and a specificity of 89%. Thus, pretreatment immunological status has a major influence on the ability of IFN-alpha to cure chronic hepatitis C, and the evaluation of perforin gene expression may help to select patients that will benefit from IFN-alpha treatment.

Fractalkine receptor expression by T lymphocyte subpopulations and in vivo production of fractalkine in human.

Expression and function of the fractalkine receptor CX3CR1 by T lymphocyte subpopulations was evaluated in healthy individuals. In CD8(+) T lymphocytes, CX3CR1 was expressed by and functional in both CD45RO(-) and CD45RO(+) cells. In CD4(+) T lymphocytes, CX3CR1 was expressed mainly by CD45RO(+) cells, and almost exclusively by activated HLA-DR(+) T lymphocytes. This receptor was functional in CD45RO(+) cells, but not in CD45RO(-) cells. Expression of fractalkine was detected by in situ hybridization and immunohistochemistry in endothelial cells of normal lung and thymus. In hyperplastic lymph nodes, fractalkine was expressed by endothelial cells of high endothelial venules and of subcapsular vessels, by follicular dendritic cells (FDC) and by some follicle lymphocytes. Fractalkine mRNA was constitutively present in the HK FDC-like cell line, and it was induced in vitro in B lymphocytes stimulated by an anti-micro or by a CD40 mAb. These findings indicate that fractalkine may contribute to the recruitment of effector T helper lymphocytes, either in peripheral tissues or in lymphoid organs. In these tissues, fractalkine and its receptor may favor contact within follicles between activated T helper lymphocytes, activated B lymphocytes and FDC, thus contributing to the maturation of the B lymphocyte response.

Human interleukin-6 is in vivo an autocrine growth factor for human herpesvirus-8-infected malignant B lymphocytes.

Human interleukin-6 (hIL-6) acts as a growth factor in several human B lymphoid cancers. As human herpesvirus-8 (HHV-8) encodes for a viral IL-6 (vIL-6), the viral cytokine may be responsible for several manifestations of HHV-8-related disorders. Using an anti-hIL-6 mAb (B-E8) which does not recognize vIL-6, we investigated the involvement of the human cytokine in the proliferation of HHV-8-positive primary effusion lymphoma (PEL) cells. In vitro, 5/5 PEL cell lines produced hIL-6 (4 to 1,200 pg/ml). The EBV- HHV-8+ cell line (BCBL-1) was adapted to grow in SCID mice. hIL-6 was detected in the serum of mice with grafts, as well as human soluble CD138 (sCD138) and human IL-10 (hIL-10). The serum level of these mediators increased with tumor progression. The effect of treatment with the B-E8 mAb on the tumor progression and survival was evaluated. This treatment significantly slowed down the tumor development: on day 54, there were more mice with low levels of sCD138 and hIL-10 in the treated group than in controls (p = 0.03 and 0.02, respectively); treatment also delayed death (median date of death was day 65 for control mice and day 84 for anti-hIL-6 mAb-treated mice; p < 0.02). Thus, hIL-6 is expressed in addition to vIL-6 in HHV-8-positive malignant B lymphocytes, and the viral cytokine does not totally substitute for human IL-6 in promoting tumor progression.

Acute activation of CD8+ T lymphocytes in interleukin-2-treated HIV-infected patients. ANRS-048 IL-2 Study Group. Agence Nationale de Recherches sur le SIDA.

CD8+ T lymphocytes play a key role in the control of HIV infection, through both cytotoxic and noncytotoxic mechanisms. To study in vivo effects of interleukin-2 (IL-2) treatment on this cell compartment, the level of activation of CD8+ T lymphocytes was evaluated before and just after 5-day administration of IL-2 in 16 HIV-infected patients. The serum level of soluble CD25 and of soluble CD8 significantly increased following IL-2 administration. The number of mRNA molecules coding for perforin and granzyme B, two enzymes that are contained in granules of cytotoxic cells, also significantly increased in peripheral blood mononuclear cells and in purified CD8+ cells (p < .001). Variations of plasma HIV viremia and perforin gene expression following IL-2 administration were inversely correlated (p = .023), suggesting that IL-2-induced activation of CD8+ T lymphocytes contributes to limit HIV replication in vivo. In contrast to perforin and granzyme B gene expression, IL-2 administration did not increase the expression of macrophage inhibitory protein-1alpha (MIP-1alpha), MIP-1beta, and regulated-on-activation normal T-expressed and secreted (RANTES) genes. These findings indicate that CD8+ T lymphocytes in HIV-infected patients are acutely activated by IL-2 treatment, which may improve long-term control of HIV infection.

Stromal cell-derived factor 1 (SDF-1) and antenatal human B cell lymphopoiesis: expression of SDF-1 by mesothelial cells and biliary ductal plate epithelial cells.

The chemokine stromal cell-derived factor 1 (SDF-1) stimulates the growth of pre-B cells in vitro, and mice with a disrupted SDF-1 gene have abnormal fetal liver B cell lymphopoiesis. The origin of SDF-1 production has not been determined yet. Using an anti-SDF-1 mAb, we performed immunohistochemical studies in four human embryos and five fetuses to define which cells express the SDF-1 protein at sites of antenatal B cell lymphopoiesis. All mesothelial cells contained SDF-1 at all stages of development, including in the intraembryonic splanchnopleuric mesoderm early into gestation. In fetal lungs and kidneys, SDF-1 was expressed by epithelial cells, and a few B lymphoid precursors, expressing V pre-B chains, were also detected. In the fetal liver, in addition to mesothelial cells, biliary epithelial cells were the only cells to contain SDF-1. Pre-B cells expressing V chains were abundant and exclusively located around the edge of portal spaces, in close contact with biliary ductal plate epithelial cells. They did not colocalize with biliary collecting ducts. Biliary ductal plate epithelial cells and liver B cell lymphopoiesis display a parallel development and disappearance during fetal life. These results indicate that early B cell lymphopoiesis in the splanchnopleura may be triggered by mesothelial cells producing SDF-1. Later into gestation, biliary ductal plate epithelial cells may support B cell lymphopoiesis, thus playing a role similar to that of epithelial cells in the avian bursa of Fabricius, and of thymic epithelial cells for T cell lymphopoiesis.

Acute upregulation of CCR-5 expression by CD4+ T lymphocytes in HIV-infected patients treated with interleukin-2. ANRS 048 IL-2 Study Group.

BACKGROUND: The treatment of HIV-infected patients with interleukin (IL)-2 causes a sustained increase in CD4+ T-lymphocyte counts, involving both naive and memory cells. However, the short-term immunological effects of IL-2, which may shed light on the mechanism of immune reconstitution by this cytokine, are unknown. OBJECTIVE: To evaluate the acute effect of IL-2 on circulating T-lymphocyte subpopulations and their expression of chemokine receptors. DESIGN AND METHODS: Flow cytometry, reverse transcriptase polymerase chain reaction and chemokine receptor function experiments were performed before and after 5 days of IL-2 administration in 30 HIV-infected patients. RESULTS: IL-2 induced an acute lymphopenia of both naive and memory T-helper (TH) lymphocytes. This was associated with a large increase in CC-chemokine receptor (CCR)-5 and CCR-2b expression by TH cells. Before IL-2 treatment, CCR-5 was mostly produced by CD62L- memory TH lymphocytes. After 5 days of IL-2 administration, the level of CCR-5 mRNA in circulating cells was 18.6 times higher than before treatment (P < 0.002). CCR-5 expression was upregulated in CD62L- memory TH lymphocytes, but also in CD62L+ memory and in naive (CD62L+ CD45RO-) TH lymphocytes. IL-2 treatment also increased the function of CCR-5 in TH cells. CONCLUSIONS: Chemokine receptors are involved in trafficking of lymphocytes. The IL-2-induced upregulation of chemokine receptors in TH cells may thus play a role in the acute effects of this cytokine in TH lymphocyte redistribution.

Antigen receptor engagement selectively induces macrophage inflammatory protein-1 alpha (MIP-1 alpha) and MIP-1 beta chemokine production in human B cells.

We show herein that B cell Ag receptor (BCR) triggering, but not stimulation by CD40 mAb and/or IL-4, rapidly induced the coordinated expression of two closely related T cell chemoattractants, macrophage inflammatory protein-1 beta (MIP-1 beta) and MIP-1 alpha, by human B cells. Naive, memory, and germinal center B cells all produced MIP-1 alpha/beta in response to BCR triggering. In contrast to MIP-1 alpha/beta, IL-8, which is spontaneously produced by germinal center B cells but not by naive and memory B cells, was not regulated by BCR triggering. Culturing follicular dendritic cell-like HK cells with activated B cells did not regulate MIP-1 alpha/beta production, but it did induce production of IL-8 by HK cells. Microchemotaxis assays showed that CD4+CD45RO+ T cells of the effector/helper phenotype actively migrated along a chemotactic gradient formed by BCR-stimulated B cells. This effect was partially blocked by anti-MIP-1 beta and anti-CC chemokine receptor 5 Ab, but not by anti-MIP-1 alpha Ab suggesting that MIP-1 beta plays a major role in this chemoattraction. Since maturation of the B cell response to a peptide Ag is mostly dependent on the availability of T cell help, the ability of Ag-stimulated B cells to recruit T cells via MIP-1 alpha/beta, may represent one possible mechanism enabling cognate interactions between rare in vivo Ag-specific T and B cells.

Administration of interleukin 13 to simian immunodeficiency virus-infected macaques: induction of intestinal epithelial atrophy.

Increase Th2 cytokine production may contribute to some clinical manifestations of HIV infection, and studies have suggested that IL-13 rather than IL-4 is involved in these conditions. We directly tested this hypothesis by administrating IL-13 to SIV-infected macaques. SIV-infected rhesus macaques received a daily subcutaneous injection for 21 days of either IL-13 (10 microg/kg/day) or a placebo. The four macaques treated with IL-13 experienced body weight loss (9.95 +/- 0.71%) related to intestinal tract damage: they all suffered from a complete atrophy of duodenal villi. This was presumably due to premature epithelial cell death: proliferating Ki67+ cells in glandular crypts were as numerous as in control animals, but many epithelial cells developed apoptosis. The duodenal mucosa was infiltrated with cells expressing CD56 and PEN5, two markers of NK cells, and there was a deregulation of local cytokine and chemokine production characterized by a decrease in IL-10 gene expression (25% of controls) and an increase in gene expression for IFN-gamma (4-fold control), MIP-1alpha (8-fold control), and MIP-1beta (13-fold control). Thus, IL-13 can induce digestive epithelial cell injury in vivo in primates infected with a retrovirus. Therefore, its role should be considered in digestive manifestations of HIV infection as well as in other disorders associated with intestinal epithelial atrophy.